The invention relates to improvements in methods of and in apparatus for making rod-shaped articles of the tobacco processing industry, such as cigarettes, cigars, cigarillos and cheroots. More particularly, the invention relates to improvements in methods of and in apparatus for making rod-shaped articles (hereinafter called cigarettes for short) from comminuted tobacco leaves or other smokable material by converting such material (hereinafter called tobacco) into a stream which is thereupon draped into a web of wrapping material to form with the wrapping material a rod ready to be subdivided into cigarettes of desired length.
Manufacturers of cigarettes strive to produce articles of unchanging quality. Particular emphasis is placed upon certain selected characteristics of cigarettes, not only by the makers of cigarettes but also by the smokers. For example, a smoker will normally prefer cigarettes having a predetermined hardness and a particular draw resistance (namely that resistance which tobacco smoke encounters to the flow toward the mouth). On the other hand, a manufacturer of cigarettes will be particularly interested in the percentage of certain ingredients which are also of interest to authorities, such as the nicotine content, the content of condensate (tar) and, at least in certain countries, the carbon monoxide content because such information must be displayed on the packets.
It is already known to regulate the making of cigarettes in such a way that the density (and hence the weight) of cigarettes remains constant. This is achieved by monitoring the density of cigarettes and by regulating the removal of surplus tobacco from the stream in dependency upon the results of the monitoring operation. However, it is not known to select in advance certain other important characteristics of the stream and/or finished cigarettes, particularly the nicotine content, the carbon monoxide content and/or the condensate (tar) content of tobacco smoke.